IMHO, only unless the OP used an empty boundary in multipart message.

https://en.wikipedia.org/wiki/MIME#Multipart_messages

Even with an empty boundary, message parts are separated by lines composed of --, followed by the (empty) boundary, followed by CR/LF. So an empty line never separates MIME message parts, it must at least begin with --. The end of all mime parts is indicated by appending another -- to the boundary.

Copying the example from Wikipedia:

MIME-Version: 1.0
Content-Type: multipart/mixed; boundary=frontier

This is a message with multiple parts in MIME format.
--frontier
Content-Type: text/plain

This is the body of the message.
--frontier
Content-Type: application/octet-stream
Content-Transfer-Encoding: base64

PGh0bWw+CiAgPGhlYWQ+CiAgPC9oZWFkPgogIDxib2R5PgogICAgPHA+VGhpcyBpcyB0aG
+Ug
Ym9keSBvZiB0aGUgbWVzc2FnZS48L3A+CiAgPC9ib2R5Pgo8L2h0bWw+Cg==
--frontier--
[download]

Changed to an empty boundary:

MIME-Version: 1.0
Content-Type: multipart/mixed; boundary=

This is a message with multiple parts in MIME format.
--
Content-Type: text/plain

This is the body of the message.
--
Content-Type: application/octet-stream
Content-Transfer-Encoding: base64

PGh0bWw+CiAgPGhlYWQ+CiAgPC9oZWFkPgogIDxib2R5PgogICAgPHA+VGhpcyBpcyB0aG
+Ug
Ym9keSBvZiB0aGUgbWVzc2FnZS48L3A+CiAgPC9ib2R5Pgo8L2h0bWw+Cg==
----
[download]

(I'm not sure if the empty boundary needs to be quoted. Nobody does that, anyway. The boundary should be a string that does not appear anywhere in the messages. In practice, you stuff in some random data, perhaps user agent, perhaps a timestamp. Maybe hash it. Just get a good chunk of line noise. See Re^5: Using Net::SMTP to send email attachments for more details.)

Alexander